Atopic diseases such as atopic dermatitis, asthma, allergic rhinitis and allergic conjunctivitis are diseases which respond hypersensively to environmental antigens or the like, to which normal subjects do not respond, and develop destruction or disorder of various organs by their own immune system. Th2 cytokines which enhance allergic responses are assumed to play a role in the onset mechanism of these diseases. Elucidation of their induction and regulatory mechanisms, therefore, has an important significance from the standpoints of physiology and pharmacology, but these mechanisms have not been clarified in detail yet.
Treatments of atopic diseases are currently known to include primarily those which rely upon avoidance from antigens, or antihistamines which compete with binding of mediators such as histamine to receptors, or anti-inflammatory steroidal agents. Development of treatment methods directed to more specific acting mechanisms is, however, hampered due to lack of appropriate laboratory animals.
Induction of an allergic response on a laboratory animal has conventionally required administration of an antigen or allergen to the animal after sensitizing the animal beforehand by repeated immunization of the animal with the antigen or allergen. In this case, simultaneous sensitization of many animals, however, requires a great deal of labor and further, may produce variations in reactivity among the individual animals, leading to a problem in the reproducibility of an experiment.
In recent years, NC/Nga mouse is attracting interests as a model animal for atopic dermatitis. Dermatitis which occurs on this mouse, however, leads to its onset for the first time in the presence of mites, and moreover, its onset rate is unstable and its symptom varies.
Laboratory animals are indispensable for the development of medicines for atopic diseases, leading to a strong outstanding desire especially for model animals of atopic dermatitis. These days, however, there is not any atopic dermatitis model animal available and provided for practical use, which has been established in genetic background, is immunologically defined and is usable for the development and research of various treatment methods and drugs under specific pathogen-free conditions.
An object of the present invention is, therefore, to create an animal useful as an atopic dermatitis model.